Preparation, characterization and application of polyaniline nanospheres to biosensing

Abstract

Polyaniline nanospheres (PANI-NS) prepared by morphological transformation of micelle polymerized camphorsulfonic acid (CSA) doped polyaniline nanotubes (PANI-NT) in the presence of ethylene glycol (EG) have been characterized by X-ray diffraction, atomic force microscopy, transmission electron microscopy, scanning electron microscopy, Fourier transform infra-red and UVVisible spectroscopy. A PANI-NS (60-80 nm) film deposited onto an indium-tin-oxide (ITO) coated glass plate by the solution casting method has been utilized for covalent immobilization of biomolecules (cholesterol oxidase (ChOx)) via N-ethyl-N 0 -(3-dimethylaminopropyl) carbodiimide (EDC) and Nhydroxysuccinimide (NHS) chemistry for fabrication of a cholesterol biosensor. The ChOx/PANI-NS/ ITO bioelectrode detects cholesterol in the concentration range of 25 to 500 mg dL À1 with sensitivity of 1.3 Â 10 À3 mA mg À1 dL and regression coefficient of 0.98. Further, this PANI-NS based bioelectrode shows fast response time (10 s), low Michaelis-Menten constant (2.5 mM) and shelf-life of 12 weeks. The spherical nanostructure observed in the final morphology of the PANI-NS film is attributed to hydrogen bonding interactions between PANI-NT and EG.

Recent advances in polyaniline based biosensors

“…Similarly, Dhand et al have investigated the performance of chemically fabricated PANI nanospheres and electrophoretically deposited nanostructured PANI as platform towards the fabrication of cholesterol biosensor. These studies have revealed that PANI nanospheres show better detection range with faster response time and shelf-life that may be attributed to the large aspect ratio of these films (Dhand et al, 2010). The integration of nanostructures and biomolecules may lead to new hybrid systems that couple the recognition or catalytic properties of biomaterials with attractive electronic and structural characteristics.…”

Polyaniline/Single‐Walled Carbon Nanotubes Composite Based Triglyceride Biosensor

“…After this mediator has been immobilized on the electrode surface, LIP and GDH are covalently attached to PANI-SWCNT composite film via amide bond formation between the ÀNHÀ and ÀNH 2 groups of PANI and À COOH group of both the enzymes using EDC as the coupling agent and NHS as the activator (Scheme 1A) [29]. For the enzyme immobilization, the optimal binding is achieved when 50 mL solution of 50 mg LIP and 10 mL solution of 10 mg GDH mixed with 0.4 M EDC and 0.1 M NHS is dropped onto 1 cm 2 of PANI-SWCNT film and kept in a humid chamber for about 4 hours.…”

Fabrication of multiwalled carbon nanotube–polyaniline/platinum nanocomposite films toward improved performance for a cholesterol amperometric biosensor

“…Doping with acid and base can interchange EB and emeraldine salt forms of PANI. EB is regarded as the most useful form of PANI due to its high stability at room temperature and its doped form is electrically conducting [19][20][21]. The conducting polymer of PANI might be greatly applied in many biosensors in virtue of its especial properties such as (1) high surface area and chemical specificities, (2) redox conductivity and polyelectrolyte characteristics, (3) direct and easy deposition on the electrode, (4) long-term environmental stability, and (5) control of thickness and low cost.…”